1. Field of the Invention
The present invention relates to an electron beam apparatus and an image producer as an application thereof, such as an image display and the like. The present invention also relates to a spacer for use in the electron beam apparatus.
2. Related Background Art
There are two types of electron emission devices currently known: a hot cathode device and a cold cathode device. As to the latter, the known devices include, for example, surface conduction electron emission devices, field emission devices (hereinafter referred to as an FE type) and metal-insulating layer-metal type electron emission devices (hereinafter referred to as an MIM type).
The surface conduction electron emission devices currently known include, for example, one disclosed by M. I. Elinson in Radio Eng. Electron Phys., 10, 1290, (1965), and the others described below.
The surface conduction electron emission devices take advantage of the phenomenon that electron emission occurs on the thin film of a small area formed on the, substrate when applying electric current parallel to the surface of the film. There are several types of surface conduction electron emission devices reported, in addition to the aforesaid device by Elinson et al. which utilizes SnO2 thin film: one utilizing Au thin film (refer to G. Dittmer: xe2x80x9cThin Solid Films,xe2x80x9d 9, 317 (1972)), one utilizing In2O3/SnO2 thin film (refer to M. Hartwell and C. G. Fonstad: xe2x80x9cIEEE Trans. ED Conf.,xe2x80x9d 519 (1975)), and one utilizing carbon thin film (refer to Hisashi Araki et al. xe2x80x9cVacuum,xe2x80x9d Vol. 26, No. 1, 22 (1983)).
FIG. 33 shows a plan view of the aforementioned device by M. Hartwell et al. as a typical example illustrating the construction of the surface conduction electron emission devices. In the figure, reference numeral 3001 designates a substrate and numeral 3004 designates a conductive thin film consisting of metal oxide and formed by sputtering. The conductive thin film 3004 is in the form of an H-shaped plan as shown in the figure. An electron emission portion 3005 is formed by conducting an energization treatment, known as energization forming which is to be described below, to the above conductive thin film 3004. The spacings L and W in the figure are set for 0.5 to 1 [mm] and 0.1 [mm], respectively. For convenience""s sake, in the above figure the electron emission portion 3005 is shown in the center of the conductive thin film 3004 in the form of a rectangle. The figure is, however, very schematic and does not necessarily represent the actual position and form of the electron emission portion.
In the aforesaid surface conduction electron emission devices, including one by M. Hartwell, it has been common that the electron emission portion 3005 is formed by conducting an energization treatment, called energization forming, to the conductive thin film 3004 prior to the execution of electron emission. Energization forming used herein means that a constant direct-current voltage or a direct-current voltage stepping up at a very slow rate of, for example, about 1 V/min is applied to both ends of the conductive thin film 3004 to pass a current therethrough and cause a local fracture, deformation or change in quality therein, so as to form the electron emission portion 3005 in a highly resistive state. In some part of the conductive thin film 3004 having undergone a local fracture, deformation or change in quality, a crack is to appear. When applying a proper voltage to the conductive thin film 3004 after the above energization forming, electric emission occurs in the vicinity of the above crack.
The known FE type devices include, for example, one disclosed by W. P. Dyke and W. W. Dolan in xe2x80x9cField Emission,xe2x80x9d Advance in Electron Physics, 8, 89 (1956) and one disclosed by C. A. Spindt in xe2x80x9cPhysical Properties of Thin-Film Field Emission Cathodes with Molybdenium cones,xe2x80x9d J. Appl. Phys., 47, 5248 (1976).
FIG. 34 shows a sectional view of the aforementioned device by C. A. Spindt et al. as a typical example illustrating the configuration of FE type devices. In the figure, reference numeral 3010 designates a substrate, numeral 3011 an emitter wiring consisting of a conductive material, numeral 3012 an emitter cone, numeral 3013 an insulating layer and numeral 3014 a gate electrode. In this device, field emission is caused at the tip portion of the emitter cone 3012 by applying a proper voltage between the emitter cone 3012 and the gate electrode 3014.
There is another example of the construction of FE type devices where, unlike the laminated structure shown in FIG. 34, an emitter and a gate electrode are arranged on the substrate almost parallel to the substrate plane.
The known MIM type devices include, for example, one disclosed by C. A. Mead in xe2x80x9cOperation of Tunnel-Emission Devices,xe2x80x9d J. Appl. Phys., 32, 646 (1961). FIG. 35 shows a typical example of the construction of MIM type devices. The figure is a sectional view, in which reference numeral 3020 designates a substrate numeral 3021 a lower electrode consisting of metal, numeral 3022 a thin insulating layer about 100 xc3x85 thick and numeral 3023 an upper electrode about 80 to 300 xc3x85 thick consisting of metal. In MIM type devices, electron emission is caused on the surface of the upper electrode 3023 by applying a proper voltage between the upper electrode 3023 and the lower electrode 3021.
The aforementioned cold cathode devices do not need a heater for heating their cathode since they allow electron emission to occur at a lower temperature than hot cathode devices. Accordingly, their structure can be simpler than that of hot cathode devices, which allows fine devices to be produced. Further, when multiple devices are densely arranged, problems such as melting substrate by heat and the like are unlikely to occur. In addition, unlike the hot cathode devices, which are slow at response because they operate only after heated with a heater, the cold cathode devices have the advantage of being quick at response.
Thus, a lot of studies have been conducted for the application of cold cathode devices.
A surface conduction electron emission device, for example, has a particularly simple structure and is easy to produce compared with the other cold cathode devices, accordingly the application of this type devices is advantageous to forming multiple devices over a large area of the substrate. Therefore, methods have been studied to arrange and drive multiple devices on the substrate, as disclosed, for example, by the present applicants in Japanese Patent Application Laid-Open No. 64-31332.
As to the application of surface conduction electron emission devices, the studies have been carried out of, for example, image producer such as an image display and an image recorder, charged beam sources and the like. For the application to an image display, the display using surface conduction electron emission devices in combination with a fluorescent substance, which emits light when electron beam is applied, has been studied as disclosed by the present applicants in U.S. Pat. No. 5,066,883, Japanese Patent Application Laid-Open No. 2-257551 and Japanese Patent Application Laid-Open No. 4-28137. An image display using surface conduction electron emission devices in combination with a fluorescent substance is expected to have properties superior to conventional ones using other methods. The above display may be superior to, for example, the liquid crystal display which has been in common use recently in that it does not need a backlight since it spontaneously emits light and in that it has a wide viewing angle.
A method for arranging and driving multiple FE type devices is disclosed, for example, by the present applicants in U.S. Pat. No 4,904,895. The known examples of the application of FE type devices to an image display include, for example, a planar image display reported by R. Meyer et al. (refer to R. Meyer: xe2x80x9cRecent Development on Micro-Tips Display at LETI,xe2x80x9d Tech. Digest of 4th Int. Vacuum Microelectronics Conf., Nagahama, pp. 6-9 (1991)).
An example of the application of multiple MIM type devices in the arranged state to an image display is disclosed by the present applicants in Japanese Patent Application Laid-Open No. 3-55738.
Among the image producer using the electron emission devices described above, a planar image display which is thin depthwise has attracted considerable attention as a replacement of the image displays utilizing cathode-ray tubes, since it is space-saving and lightweight.
FIG. 36 is a perspective view of one example of the display panel constituting a planar image display, partially broken away to show the inside structure.
In the figure, reference numeral 3115 designates rear plate, numeral 3116 a side wall and numeral 3117 a face plate. And the rear plate 3115, the side wall 3116 and the face plate 3117 make up an outer enclosure (hermetic container) for keeping the inside of the panel cell vacuum. On the rear plate 3115 a substrate 3111 is fixed, while on the substrate 3111 Nxc3x97M cold cathode devices are formed (wherein N, M are positive integers not lower than 2 and they are properly set according to the number of pixels to be displayed). The above Nxc3x97M cold cathode devices 3112 are wired with M lines of row wiring 3113 and N lines of column wiring 3114 as shown in FIG. 27. The portion consisting of the substrate 3111, the cold cathode devices 3112, the row wiring 3113 and the column wiring 3114 is referred to as a multiple electron beam source. Between the row wiring 3113 and the column wiring 3114 an insulating layer (not shown in the figure) is formed at least at each portion where the row wiring intersects the column wiring. As a result, the row wiring 3113 and the column wiring 3114 can be kept electrically separated from each other.
On the underside of the face plate 3117, a fluorescent film 3118 is formed which consists of fluorescent substances of three primary colors: red (R), green (G) and blue (B) (not shown in the figure). Between adjacent fluorescent substances each of which is colored in any one of the above primary colors and constitutes the fluorescent film 3118, a black substance (not shown in the figure) is provided. And on the surface of the fluorescent film 3118 which faces the rear plate 3115, a metal back 3119 consisting of Al and etc. is formed.
Dx1 to Dxm, Dy1 to Dyn and Hv are electrical connection terminals having a hermetic structure for electrically connecting the above display panel with an electric circuit, which does not appear in the figure. Dx1 to Dxm, Dy1 to Dyn and Hv are electrically connected with the raw wiring 3113 of the multiple electron beam source, the column wiring 3114 of the multiple electron beam source and the metal back 3119, respectively.
The interior of the above hermetic container is kept at a vacuum of about 10xe2x88x926 Torr (1.33xc3x9710xe2x88x924 Pa). As the display area of the image display becomes larger, some means becomes necessary to prevent the rear plate 3115 and the face plate 3117 from undergoing deformation or fracture due to the difference in atmospheric pressure between the interior and the exterior of the hermetic container. The use of the method in which the rear plate 3115 and the face plate 3117 are made thicker not only increases weight of the image display, but causes distortion of images as well as parallax when viewing the display at an angle. Contrary to this, in FIG. 36 are provided structural supports (referred to as spacer or rib) 3120 made of a relatively thin glass plate for supporting atmospheric pressure. The spacing between the substrate 3111, which has a multiple electron beam source formed on it, and the face plate 3117, which has a fluorescent film 3118 formed on it, is usually kept submillimeter to several millimeters, and the interior of the hermetic container is kept at a high vacuum as described above.
When applying voltage to each cold cathode device 3112 in an image display with the display panel described above through the terminals, Dx1 to Dxm and Dy1 to Dyn, outside the container, electrons are emitted from each cold cathode device 3112. At the same time, a high voltage of several hundreds-volt to several-kilovolt is applied to the metal back 3119 through the terminal Hv outside the container to accelerate the emitted electrons above and force them to collide with the internal surface of the face plate 3117. This allows each colored fluorescent substance constituting the fluorescent film 3118 to be excited and emit light, as a result of which images are displayed.
The aforementioned display panel for image displays has, however, the following problems. First, the spacer 3120 may be charged when some of the electrons emitted from its vicinity hit it or when the ions emitted due to the action of the emitted electrons deposit to it. The orbit of the electrons emitted from the cold cathode device 3112 is deformed due to the charged spacer, so that the electrons reach the place other than the normal one, which leads to the distortion of the image in the vicinity of the spacer.
Second, there is a fear that a creeping discharge should occur along the surface of the spacer 3120 disposed between the multiple electron beam source and the face plate 3117, since a high voltage of several hundreds-volt or higher (that is, a high electric field of 1 kV/mm or higher) is applied therebetween to accelerate the electrons emitted from the cold cathode device 3112. An electric discharge is likely to be induced, particularly when the spacer is in the charged state as described above.
In order to solve this problem, there is proposed a method in U.S. Pat. No. 5,760,538 in which the electrical charge contained in spacers be neutralized by passing an infinitesimal current therethrough. In the above patent, an infinitesimal current is allowed to pass through the surface of the spacers by forming a highly resistant thin film as an antistatic film thereon. The antistatic film used in the above patent is a thin film of tin oxide, a mixed crystal thin film of tin oxide and indium oxide, or a metal thin film.
The use of the method in which electrical charge is neutralized with a highly resistant thin film sometimes leaves the problem of insufficient reduction of image distortion unsolved. The principal factor underlying this problem is considered to be the concentration of electrical charge in the vicinity of the junction portion due to the insufficient electrical junction between the spacers with a highly resistant thin film and the upper and lower substrates, that is, the face plate (hereinafter referred to as xe2x80x9cFPxe2x80x9d) and the rear plate (hereinafter referred to as xe2x80x9cRPxe2x80x9d). In order to solve this problem, there is proposed a method in which the end faces of the spacer facing FP and RP, respectively, are coated with the material whose resistivity is lower than a metal thin film or a highly resistive film within the range of about 100 to 1000 micron so as to ensure its electrical contact with the upper and lower substrates and control its electrification due to the incidence of the reflected electrons from the face plate, as disclosed in Japanese Patent Application Laid-Open No. 8-180821 and Japanese Patent Application Laid-Open No. 10-144203.
Even with such a means given to the highly resistive film and the means for controlling the orbit of emitted electrons, as well as with the formation of low resistive film portion for a better electrical contact as described below, electrification of the spacers cannot be sufficiently controlled depending on the other design parameters of the electron beam apparatus, such as materials and film thickness of its face plate, shape, and anode accelerating voltage, and there still exist problems of, for example, displacement of light emitting points and occurrence of an infinitesimal discharge in the vicinity of the spacers due to the insufficient control.
The cause of such electrification is not clarified in detail, it is, however, considered that the factors lie upon the following background.
Presumably, the cause of electrification of the spacers is such that there may exist some factors which effectively increase the capacitance and resistance of the spacers as described below, or the spacers are exposed to the reflected electrons from the cold cathode devices 3112 close thereto other than the most closest ones during their non-selective period and also exposed to the abnormal field emission from the field concentration region in the vicinity of the spacer-cathode junction. In addition, it is considered to be another cause of the electrification that control of the secondary emission coefficient on the surface of the spacers is not accounted for in design.
[Background 1] Restriction by the relaxation time constant of a highly resistive film on spacers The progress of electrification and relaxation in any region of the surface of a spacer can be considered as a time delay of the charged electric potential corresponding to the injection current by the application of a charged dielectric model.
FIG. 12 illustrates a model which represents the relaxation by capacitance resistant devices in the case of looking at upper and lower electrodes from a current injection region, when an effective injection current ic is supplied from a current source to an arbitrary position z on the surface of a spacer. In the figure, Va designates a voltage applied from a voltage source to an anode and ic an effective injection current supplied to the position at a height of zh (wherein h corresponds to the height of a spacer, 0 less than z less than 1). The effective injection current corresponds to the difference between a secondary current and a primary current. C1 and R1 designate values of capacitance and resistance, respectively, which specify the relaxation time constant between the injection region and the anode, while C2 and R2 values of capacitance and resistance, respectively, which specify the relaxation time constant between the injection region and the cathode. When the resistance and the capacitance distribute uniformly in the altitude direction, C1, C2, R1 and R2 are described using the resistance of the spacer R and the capacitance C by C/(1xe2x88x92z), R(1xe2x88x92z),C/z and Rz, respectively.
Since the principle of superposition should hold for the injection current in any position, the electric potential in the region of an arbitrary altitude on the spacer can be specified without losing generality if considering the electrification process in the following manner; first a high voltage Va from a voltage source is applied between the anode and the cathode, then the electronic current entering from the vacuum side to the position z in the aimed region is treated as an effective injection current Ic which is equivalent to the difference between the entered and emitted currents, and finally performing formularization with an equivalent circuit to which the effective injection current Ic as a current source is supplied, as shown in FIG. 12.
Now, in order to design a suitable spacer construction, formularization of a relaxation process will be performed taking a concrete example of the charged electric potential on the spacer having an insulating or highly resistive film formed on it and suitable for the electron beam emission apparatus of the present invention. For simplification, it is assumed that distribution of electric constant is uniform on the surface of the spacer. First, formularization is performed treating the rate of effective injection charge to the surface of the spacer as amount of current supplied from a current source and taking into account the energy distribution and incident angle distribution of incident electrons. The result is as follows:
amount of electronic current emitted from the electron emission device Ie
proportion of the incident electrons at an altitude of zh (0 less than z less than 1) xcex2ij 
secondary electron emission coefficient at an altitude of zh (0xe2x88x92z less than 1) xcex4ij 
provided that superscripts i, j correspond to incident energy and incident angle, respectively, amount of primary electronic current in the position z Ip
Ip=xcexa3xcexa3Ipij=xcexa3xcexa3xcex2ijxc3x97Ie
amount of secondary electronic current in the position z Is
Is=xcexa3xcexa3xcex4ijxc3x97Ipij=xcexa3xcexa3xcex4ijxc3x97xcex2ijxc3x97Ie
injection rate of the electrical charge in the position z Ic
Ic=xcexa3xcexa3(xcex4ijxe2x88x921)xc3x97Ipij=xcexa3xcexa3(xcex4ijxe2x88x921)xc3x97xcex2ijxc3x97Ie
Finally, the rate of injection charge Ic can be described as
Ic=Pxc3x97Iexe2x80x83xe2x80x83General Formula (2)
wherein P is described as P=xcexa3xcexa3(xcex4ijxe2x88x921)xc3x97xcex2ij and is a coefficient independent of Ie, it is, however, assumed that in reality P changes as the progress of electrification.
Then, for the arrangement of the capacitance and resistance of the spacer film seen from the injection region, it is assumed for simplification that there exists neither resistance variation nor capacitance variation in the altitudinal direction of the spacer (this corresponds to the direction in which a high voltage is applied between anode and cathode). At this time, when the resistance and capacitance in the direction parallel to the surface of the spacer seen from anode/cathode are represented by R and C, the altitude of the spacer h, and the altitude of the injection region zh (0xe2x89xa6zxe2x89xa61, on the anode side z=1), the electric constant existing above and below the injection region is specified for the position z. Further, since a voltage from the voltage source is applied between the anode and the cathode, an effective impedance Z is dealt with as 0. Thus, it is understood that the injected electrical charge undergoes relaxation through the parallel resistance and the parallel capacitance of each resistance and capacitance lying above and below the injection region. The resistance and the capacitance between the injection region in the position z and GND are described by z(1xe2x88x92z)R and C/z+C/(1xe2x88x92z), respectively, and response time constant xcfx84 of the relaxation path corresponds to the product of the master resistance and capacitance of the spacer, that is, CR at an arbitrary position.
The electric potential in any position at this time is described as a function of time using the solution obtained by setting up a differential equation concerning a current for the entire close of the aforementioned equivalent circuit shown in FIG. 12.
When the time of starting electron emission is shown by t=0, provided that electron emission device is continuously driven, xcex94V(t) which represents the progress of charged electric potential in the injection region is described by the following equation,
xcex94V(t)=z(1xe2x88x92z)Ric(1xe2x88x92exp(xe2x88x92t/xcfx84))xe2x80x83xe2x80x83General Formula (3)
and it is clear that the progress of charged electric potential depends on the product of the resistance R and effective injection current Ic.
When plotting time in abscissa and the amount of the emission current from electron emission device and the time of emitting the charged electric potential electrons on the spacer in ordinate, setting quiescent time (that is, selective period, non-selective period) for t1 seconds, and repeating the drive of the device every t2 seconds, as shown in FIG. 5, the charged electric potential xcex94V at the end of the first period (t1+t2 seconds) is described using the general formula (3) as follows:
xcex94V(t)=z(1xe2x88x92z)Ric(1xe2x88x92exp(xe2x88x92t1/xcfx84)) exp(xe2x88x92txcexa3)xe2x80x83xe2x80x83General Formula (4)
And it is assumed that electrical charge is accumulated every time the devices close to the spacer are driven, provided that t2 greater than  greater than xcfx84 or t1 less than  less than xcfx84 does not hold. The relaxation process of electrification of the spacer is thus described.
On the other hand, the change in the position of a beam with the amount of electrons emitted during the selective period t1 (Duty dependency) is a problem for a display device, however such Duty dependency in the light emitting position can be dealt with as a change of xcex94V shown by the general formula (3) corresponding to the amount of emitted electrons (the product of Ie and pulse width), accordingly both sides of the general formula (3) are differentiated by the amount of emitted electrons (the product of Ie and pulse width).             xe2x80x83        ⁢          General      ⁢              xe2x80x83            ⁢      Formula      ⁢              xe2x80x83            ⁢              (        5        )                                                                                    ⅆ                Δ                            ⁢                              xe2x80x83                            ⁢                              V                ⁡                                  (                  t                  )                                                                    ⅆ                              (                                                      I                    e                                    ⁢                                      t                    1                                                  )                                              =                                    z              ⁡                              (                                  1                  -                  z                                )                                      ⁢            R            ⁢                          {                                                                    P                    ⁡                                          (                                              1                        -                                                  exp                          ⁡                                                      (                                                                                          -                                                                  t                                  1                                                                                            /                              τ                                                        )                                                                                              )                                                        t1                                +                                                      P                    ⁢                                          xe2x80x83                                        ⁢                                          exp                      ⁡                                              (                                                                              -                                                          t                              1                                                                                /                          τ                                                )                                                                              τ                                            }                                                                    =                                                    z                ⁡                                  (                                      1                    -                    x                                    )                                            C                        ⁢                          P                              t                1                                      ⁢                          {                              τ                +                                                      (                                                                  t                        1                                            -                      τ                                        )                                    ⁢                                      exp                    ⁡                                          (                                                                        -                                                      t                            1                                                                          /                        τ                                            )                                                                                  }                                          
The general formula (5) is simplified by the driving conditions and the material constant. When the material is insulating or selective period is very short, CR=xcfx84 greater than  greater than t1 holds, and the following formula is established.                                                         ⅆ              Δ                        ⁢                          xe2x80x83                        ⁢                          V              ⁡                              (                t                )                                                          ⅆ                          (                                                I                  e                                ⁢                                  t                  1                                            )                                      =                                            z              ⁡                              (                                  1                  -                  z                                )                                      ⁢            P                    C                                    General        ⁢                  xe2x80x83                ⁢        Formula        ⁢                  xe2x80x83                ⁢                  (          6          )                    
When the material is low resistant or selective period is very long, CR=xcfx84 less than  less than t1 holds, and the following formula is established.                                                         ⅆ              Δ                        ⁢                          xe2x80x83                        ⁢                          V              ⁡                              (                t                )                                                          ⅆ                          (                                                I                  e                                ⁢                                  t                  1                                            )                                      =                                            z              ⁡                              (                                  1                  -                  z                                )                                      ⁢            PR                                t            1                                              General        ⁢                  xe2x80x83                ⁢        Formula        ⁢                  xe2x80x83                ⁢                  (          7          )                    
Now parameters specifying Duty dependency in the light emitting position, that is, tone dependency during the selective period will be explained based on the above formularization.
In terms of the conditions under which an accelerating voltage between anode and cathode is maintained, preferably a spacer has some degree of insulating property or high resistance in the direction parallel to its surface. Accordingly, when taking into account Duty dependency of charged electric potential in any position, preferably the general formula (6) is applied. Thus, in order to control Duty dependency, dielectric constant or the section area of the spacer material needs to be enlarged. The controllable range of dielectric constant in material is, however, extremely limited compared with specific resistance, and as for film thickness, it is impossible to ensure an effective dimension for the reason related to processes. Thus, control of parameter P is required.
Further, in terms of the increase in effect of electrification relaxation during quiescent time, if electrons are injected into a spacer in a repetition period shorter than the time constant specified by resistance and capacitance, charges are accumulated, as described with respect to the above general formula (4). Even when the material is applied to the highly resistive film on the surface of the spacer whose relaxation time constant is smaller than the line non-selective period of electron emission device t2 second (≅selective periodxc3x97the number of scanning lines), cumulative charge can be formed. Thus the design of relaxation time xcfx84 aiming at control of the resistance alone is considered to be insufficient for antistatic measures.
In any case, it is difficult to design suitable conditions under which electrification is restricted as long as control of resistance and capacitance alone is aimed at, for this purpose, the control of secondary electron emission coefficient is required
[Background 2] Generally secondary electron emission coefficient largely depends on the incident angle of incident electrons, and secondary electron emission coefficient xcex4 doubles almost exponentially by enlarging the incident angle.
Generally, in cases where primary electrons enter the smooth surface as shown in FIG. 14, when the incident angle is represented by xcex8 [degree] (xe2x88x9290 less than xcex8 less than 90), incident energy by Ep [keV], the distance incident electrons penetrate into the film by d [xc3x85], absorption coefficient of secondary by xcex1 [1/xc3x85], the mean energy of primary electrons needed for the generation of secondary electrons in the film by "xgr" [eV] and the probability of secondary electrons escaping from the surface to vacuum by B, secondary electron emission coefficient is quantitatively described using parameters A, n describing the energy loss process of primary electrons in the film by the following general formula (0).                     δ        =                              B                          4              ⁢                              xe2x80x83                            ⁢              ξ                                ⁢                                    (                              An                                  α                  xe2x80x2                                            )                                      1              n                                ⁢                                                    (                                                      α                    xe2x80x2                                    ⁢                                      d                    p                                                  )                                                              1                  n                                -                1                                      ⁡                          [                              1                -                                                      {                                          1                      +                                                                        (                                                                                    1                              γ                                                        -                            1                                                    )                                                ⁢                                                  α                          xe2x80x2                                                ⁢                                                  d                          p                                                                                      }                                    ⁢                                      exp                    ⁡                                          (                                                                        -                                                      α                            xe2x80x2                                                                          ⁢                                                  d                          p                                                                    )                                                                                  ]                                                          General        ⁢                  xe2x80x83                ⁢        Formula        ⁢                  xe2x80x83                ⁢                  (          0          )                    
wherein parameters xcex1, xcex3, dp are specified by the following relationship:
xcex1xe2x80x2=xcex1 cos xcex8
xcex3=1+m1xc3x97(xcex1xe2x80x2dp)xe2x88x92m2, m1=0.68273, m2=0.86212
  dp  =            E      p      n        An  
The incident energy dependency of secondary electron emission energy shown by the above general formula (0) generally has an angle property with peaks, and in many cases, it has two incident energies with which the peak value of secondary electron emission coefficient xcex4 exceeds 1 and the relation xcex4=1 is satisfied. In the incident energy between these two cross-point energies, secondary electron emission coefficient is positive, which means the generation of positive charge. Of the two cross-point energies, the smaller one is referred to as a first cross-point energy E1 and the bigger one a second cross-point energy E2.
Here, the incident angle dependency of secondary electron emission coefficient standardized in the general formula (0) for the vertical incidence of 0 degree, that is, xcex8=0 can be an index for evaluating the secondary electron emission multiplication effect at an angle.
This is shown below as a general formula (1),                                           δ            θ                                δ            0                          =                                                                                                  1                    -                                          {                                              1                        -                                                                                                            m                              0                                                        ⁢                            cos                            ⁢                                                          xe2x80x83                                                        ⁢                            θ                                                                                1                            +                                                                                                                            (                                                                      m                                    1                                                                    )                                                                                                  -                                  1                                                                                            xc3x97                                                                                                (                                                                                                            m                                      0                                                                        ⁢                                    cos                                    ⁢                                                                          xe2x80x83                                                                        ⁢                                    θ                                                                    )                                                                                                  m                                  2                                                                                                                                                                                        }                                                                                                                                        exp                    ⁡                                          (                                                                        -                                                      m                            0                                                                          ⁢                        cos                        ⁢                                                  xe2x80x83                                                ⁢                        θ                                            )                                                                                                          1              -                                                {                                      1                    -                                                                  m                        0                                                                    1                        +                                                                                                            (                                                              m                                1                                                            )                                                                                      -                              1                                                                                xc3x97                                                      m                            0                                                          m                              2                                                                                                                                                            }                                ⁢                                  exp                  ⁡                                      (                                          -                                              m                        0                                                              )                                                                                xc3x97                      1                          cos              ⁢                              xe2x80x83                            ⁢              θ                                                          General        ⁢                  xe2x80x83                ⁢        Formula        ⁢                  xe2x80x83                ⁢                  (          1          )                    
wherein parameters m1, m2 are constants having the following values:
m1=0.68273, m2=0.86212
In the general formula (1), m is equal to and which is the product of the absorption coefficient of secondary electrons xcex10 and the penetration distance of primary electrons d, is a function of incident energy, and can be a positive real number. Hereinafter m0 is referred to as incident angle multiplication coefficient of secondary electron emission coefficient, because of its characteristics. In the above general formula (1), m0 shows a tendency to increase monotonously with the incident angle |xcex8| under arbitrary incident energy conditions, then rapidly increases where the incident angle becomes about 90 degrees. This is because the primary electrons enter the surface at an angle and the distribution of the secondary electron generating sites shifts near to the surface of the film. For this reason, the proportion of the electrons increases which are emitted into vacuum without recombining and therefore vanishing. This can be understood as an apparent reduction of the absorption coefficient of secondary electrons xcex1 to xcex1 cos xcex8. In the smooth thin film formed on the smooth surface of a spacer as a spacer material, for example, many antistatic films have an incident angle multiplication coefficient of secondary electron emission coefficient m0 larger than 10, provided that the incident energy having a positive secondary electron emission coefficient, which is larger than the first cross-point energy and smaller than the second cross-point energy, is 1 keV. This increases the positive electrification with the increase in the incident angle and is the big cause of the positive electrification of the spacer material. The enlarged incident angle multiplication effect of secondary electron emission coefficient is shown in FIG. 15 with black boxes.
[Background 3] The distribution of the incident angle to a spacer is large, in addition, the incident electrons entering the surface at a large incident angle are predominant.
There exist various routes for the electrons"" incidence, they are, however, represented roughly by three particular routes. The first one is a direct incidence of the electrons emitted from electron emission devices. In this case, the incident angle is as large as about 80 to 86 degrees, though it depends on the degree of distortion in the electric field near the spacer and other designed values of the apparatus, and its incident mode is a large incident angle and high incident energy. Further, it has a feature such that, since the distance between the spacer and electron emission device close thereto is short, the amount of incident electrons is very large. The second one is an indirect incidence of the electrons reflected from a face plate to its surroundings. In this route, the distribution of the incident angle expands from 0 to large degrees, and the incident energy also has a distribution, but its range is smaller than that of the incident energy in the first route. The third one is re-incidence to the surface of the spacer of the incident electrons of the first and the second routes or the electrons emitted from field concentration points. This route is considered to occur because electrons are apt to re-enter the region in the locally positively charged state compared to other regions. In this case also, the incident angle has a distribution. Since a high electric field of about several kV/cm to several tens kV/cm is usually applied in the creeping direction as an accelerating voltage, the vertical incidence of electrons is modulated to an incidence at a large angle. Thus, incident electrons passing through any route have an incident angle distribution, and an effective charge injection is performed through the positive charge formed inside of a solid by the incident electrons entering at a large angle. Of the incident modes described above, the direct incident electrons of the first route is usually predominant over the positive charge in question, they are, however, dependent on the driving state and the design of electron emission device, and they can sometimes leave the problem unsolved of the reflected electrons from a face plate and the re-incidence of multiple scattered electrons described below.
[Background 4] Multiple electron emission on the surface
The secondary electrons once emitted from the surface of a spacer have a relatively small initial energy of at most 50 eV. Although in space they receive energy from the electric field between the anode and cathode, since situations in which the spacer is charged positively often occur, there exist many electrons plunging into the positively charged region on the spacer as well as the electrons reaching the anode. These electrons are problematic because they accumulate the positive charge on the spacer cumulatively while repeating their incidence at a low incident energy and a large incident angle and emission alternately. Thus, control of the above multiple electron emission is the subject for study.
Now the above backgrounds will be abstracted. As apparent from Background 1, there are some cases where the film designed taking into account resistant value alone is not perfect since the range within which the dielectric constant and resistant value of the film can be selected is restricted, and in such a case it is important to restrict the amount of effective current injected into the film, or to restrict secondary electron emission coefficient.
As apparent from Backgrounds 2 and 3, in the design of the spacer""s surface the reduction of incident angle dependency of secondary electron emission coefficient and the absolute value thereof is a subject, since electrification by the electrons with a large incident angle is predominant over the real electron emission devices. Further, Background 4 shows that it is important to reduce the cumulative emission phenomenon of electrons to control the cumulative positive accumulation of multiple scattered electrons. These are the subjects of the art of the present invention.
As described so far taking a spacer for example, there are some cases where there exists a member in a hermetic container within an electron emission apparatus which may be exposed to electrons, and the effect of the member due to its electrification is desired to be relaxed. The effects include, for example, variation of the position exposed to the electrons and occurrence of creeping discharge. The present patent application provides an invention which implements a construction enabling the relaxation of the above effects.
Empirically, the above formulae (0) and (1) are satisfied in almost all the materials, and the incident angle multiplication coefficient of secondary electron emission coefficient m0 is obtained by fitting experimental values in the general formula (1). m0 can be used as an index of incident angle dependency of secondary electron emission coefficient since it is highly reproductive.
According to the present inventors"" detailed examination, many inorganic materials having a low secondary electron emission coefficient which have been considered to be suitable for spacers show a strong incident angle dependency and have an incident angle multiplication coefficient of secondary electron emission coefficient m0 of 10 or larger. This is a significant cause of positive electrification of spacers within image displays of the electron beam emission type where many electrons enter the surface of the spacer at an angle.
[Ideal State Derived From Theoretical Equation]
What should be done to reduce incident angle multiplication coefficient of secondary electron emission coefficient m0 as well as to reduce secondary electron emission coefficient xcex40 for the vertical impedance? After the present inventors"" detailed examination, it was found that the above subject can be accomplished by satisfying the following requirements. Specifically, it is considered that the methods grouped into two major categories can be used in order to relax incident angle dependency.
Those are the methods for relaxing the uniformity of incident angle itself and for reducing surface effect as a property on material side, that is, the ratio of penetration depth of primary electrons to penetration depth of secondary electrons: d/xcex.
(1) Dispersion of Incident Angle of Primary Electrons
Incident angle is allowed to have an infinitesimal distribution in the normal direction on the interface considered as a surface, so that it is not restricted to the angle specified by the outside. Thus the incident angle defined on a local basis has a distribution with respect to the angle defined on a broader basis, which allows dependency on incident angle to be relaxed. Since dependency on incident angle shows the property of rapidly increasing when incident angle is close to 90 degrees, relaxation by the dispersion of incident angle is significantly effective.
(2) Reduction of the Ratio of Penetration Depth of Primary Electrons to Penetration Depth of Secondary Electrons
Since the penetration depth of electrons into a solid is proportional to the reciprocal of free electron density xcfx81Zeff/Aeff, a larger free electron density makes possible a smaller incident angle multiplication coefficient of secondary electron emission coefficient m0. In the devices other than hydrogen, values of Zeff/Aeff are in the range of 2 to 2.5, and since its variation is smaller than that of xcfx81, the penetration depth is specified by the specific gravity xcfx81 of each solid. In other words, when primary electrons have an equal incident energy, their penetration depth becomes smaller in the film having a larger density xcfx81. Then, since m0=d/xcex (wherein xcex is escape depth of secondary electrons, xcex=1/xcex1), the restriction of incident angle multiplication coefficient of secondary electron emission coefficient m0 is understood as the restriction of the ratio of penetration depth of primary electrons to penetration depth of secondary electrons within the medium.
In a uniform single material system, however, it is very difficult to control the relationship between xcex and d independently. After the present inventors"" examination, it was found that, provided that the spacer undergoes positive electrification which is the main subject when considering the electrification of the spacer, incident angle multiplication coefficient of secondary electron emission coefficient m0 often has a value of 10 or larger for the primary electrons whose incident energy is the first cross-point energy E1 or more and the second cross-point energy E2 or less.
After the present inventors detailed examination, it was found that the following structures satisfy the requirements for the construction in which the above processes (1) and (2) are performed.
According to the result of the present inventor""s examination, the escape depth of secondary electrons xcex is made to disperse and increase depthwise by constructing the surface of the spacer in such a manner that the incident angle of primary electrons have a distribution in the direction of film thickness. Because of xcexxc2x7d in many regions within a solid from the difference between the energies of electrons, the increasing rate of d with the dispersion of incident angle in the surface position is infinitesimal compared with the increasing rate of xcex, as a result, d/xcex value becomes small and incident angle multiplication coefficient of secondary electron emission coefficient m0 is reduced. The above method in which incident angle is allowed to have a distribution in the direction of film thickness on the surface of the spacer is implemented by giving the surface of the spacer a network structure in which multiple localized parts are depressed and arranged in a intricate manner.
Increase in xcex was attempted with these methods, and it is found that the application of a suitable design allows incident angle multiplication coefficient of secondary electron emission coefficient m0 to be reduced to about one third or smaller as compared to the conventional ones, that is, to be reduced to about 3.
The process of reducing incident angle dependency of secondary electron emission using the network structure consisting of an intricate surface described above is understood as follows.
Both of the primary and secondary electrons traveling in the highly resistive film portion gradually lose their energy while interacting with the atoms within the medium and repeating collision and scattering. In such a situation, their penetration depth and energy decreasing rate largely depend on the electron density of the medium they pass through. In the medium having a high electron density, since the probability of their scattering is high, their penetration depth becomes small. In addition, since the energy decreasing rate for a certain penetration distance is large, the amount of secondary electrons generated for unit depth increases. Thus, in the structure having a high electron density, in other words, in the material having a large specific gravity, penetration depth of electrons is smaller and the amount of secondary electrons generated within the is medium is larger than those in the material having a small specific gravity.
When taking into account the behavior of the secondary electrons generated at the interface of the media different in electron density while taking into account the differences in penetration depth and generation amount, it is considered microscopically that a phenomenon occurs that secondary electrons are emitted from the region where electron density is high into the region where electron density is low.
In cases where the above interface is formed unevenly and consequently the surface area is increased, electrons traveling in the low electron density region where penetration depth of incident electrons is large reach again its interface with the high electron density region, thus they lose their energy. Charges remain in the film for a certain period of time in the dielectric polarization, they, however, recombine with positive holes and vanish within the film in the end. After all, most of these electrons are not emitted into vacuum, and the amount of secondary electron emission is decreased.
In the embodiment of the present invention, a highly resistive film and vacuum are utilized as the two regions different from each other in electron density, and the surface of the foundation underlying the above highly resistive film is made uneven to form an intricate interface. In particular, a suitably intricate interface is formed in such a manner that the thickness of the resistive film is made smaller than the height difference between the highest and lowest portions of the uneven foundation.
Table 1 shows the processes implemented by the embodiment of the present invention in an arranged manner.
This structure is allowed to have a function of controlling secondary electrons by dealing with the two regions each of which has a different penetration depth due to the difference in electron density, as an interface and if the structure is constructed in such a manner that an interface of the two regions different in electron density distributes in the film, it can realize the same effects without limiting the material to a specific highly resistive material.
The invention of an electron beam apparatus according to the present application is constructed as follows.
An electron beam apparatus comprising a hermetic container which includes an electron source having electron emission devices and targets exposed to the electrons emitted from the above electron source and further comprising a first member within the above hermetic container, characterized in that the value of the incident angle multiplication coefficient of secondary electron emission coefficient m0, which is a parameter of the following formula:             δ      θ              δ      o        =                    1        -                              {                          1              -                                                                    m                    0                                    ⁢                  cos                  ⁢                                      xe2x80x83                                    ⁢                  θ                                                  1                  +                                                                                    (                                                  m                          1                                                )                                                                    -                        1                                                              xc3x97                                                                  (                                                                              m                            0                                                    ⁢                          cos                          ⁢                                                      xe2x80x83                                                    ⁢                          θ                                                )                                                                    m                        2                                                                                                                  }                    ⁢                      exp            ⁡                          (                                                -                                      m                    0                                                  ⁢                cos                ⁢                                  xe2x80x83                                ⁢                θ                            )                                                  1        -                              {                          1              -                                                m                  0                                                  1                  +                                                                                    (                                                  m                          1                                                )                                                                    -                        1                                                              xc3x97                                          m                      0                                              m                        2                                                                                                                  }                    ⁢                      exp            ⁡                          (                              -                                  m                  0                                            )                                            xc3x97          1              cos        ⁢                  xe2x80x83                ⁢        θ            
is 10 or less,
when obtaining it from the value of secondary electron emission coefficient measured under the conditions that incident energy is 1 keV and incident angle is 0 degree as well as the values measured under the conditions that incident energy is 1 keV and incident angles xcex8 are 20, 40, 60 and 80 degrees by conducting a regression analysis by the least square method in the above general formula, provided that the second electron emission coefficient of the surface of the above first member has two incident energies which satisfy the second electron emission coefficient xcex4=1 under the vertical incident conditions, and that when the larger energy of the above two energies satisfying said condition xcex4=1 is referred to as a second cross-point energy, the secondary electron emission coefficients for the primary electrons whose incident angles are xcex8 and 0 degrees are represented by
xcex4xcex8, xcex40, respectively, and
m1, m2 have the values
m1=0.68273
m2=0.86212, respectively,
in the incident energy equal to or lower than the second cross-point energy.
This invention is particularly effective in the electron beam apparatus having a construction such that it comprises a hermetic container including an electron source and targets and further comprises a first member exposed to electrons within the hermetic container. The first member includes, for example, a member restricting the deformation and fracture of the hermetic container.
The measurement of the second electron emission coefficient and the determination of the incident angle multiplication coefficient of secondary electron emission coefficient m0 are carried out as described below. First, for the measurement of secondary electron emission coefficient, a general-purpose scanning electron microscope (SEM) equipped with an electronic ammeter is used. For the measurement of primary electron current, Faraday cup is used. The amount of the secondary electron current is defined using a detector with collectors (for example, MCP or the like is available). Alternatively, it may be obtained from the specimen current and the primary electron current using the relationships of continuous law of the specimen current passing through the specimen portion, the primary current and the secondary current. Incident angle multiplication coefficient of secondary electron emission coefficient m0 can be obtained by conducting the measurement at an incident angle of 0 and at an incident angle of other than 0 under the same incident energy conditions. It is a particularly good way to define different incident angles as xcex8-xcex4 property and perform regression analysis (fitting) in general formula (1) by the least square method. In this patent application, the above fitting was performed using the secondary device emission coefficients measured at an incident angle of 0, 20, 40, 60 and 80 degrees. As a spot diameter, when the first member has an uneven structure, the size is employed which is larger than the pitch of the unevenness, in particular, which makes it possible to simultaneously expose two cycles or more of unevenness to electrons. The measurement was conducted at a vacuum of 10xe2x88x927 Torr (1.3xc3x9710xe2x88x925 Pa) or lower at room temperature (20xc2x0 C.).
It is more preferable that the incident angle multiplication coefficient of secondary electron emission coefficient m0 is 5 or less which is obtained from the value of the secondary electron emission coefficient measured under the conditions that the incident energy is 1 keV and the incident angle is 0 degree as well as the values measured under the conditions that the incident energy is 1 keV and the incident angles are 20, 40,60 and 80 degrees by performing regression analysis in general formula (1) by the least square method in the incident energy equal to or lower than the above second cross-point energy.
Suitably the above first member has an uneven geometry at least on a part of its surface.
The above requirements can be met when constructing the above first member in such a manner that it comprises a substrate having an uneven geometry at least on a part of its surface and a film coating the above uneven geometry part, in addition, that the thickness of the above film becomes smaller than the height difference between the top and lowest portions of the above uneven geometry part.
Here, the thickness of the film on the uneven part of the substrate is measured in the following manner. That is to say, a section is made by cutting off the film perpendicular to the surface of the spacer and exposed. The thickness can be measured at the above section by the section SEM. The film thickness to be measured shall be that of the lowest portion of the concavity on the substrate. When evaluating the thickness by the section SEM, a metal film deposited by sputtering may be provided as a pretreatment. This allows the local charge-up due to the insulating property of the specimen to be restricted.
The above substrate may be any of a single substrate and a laminated substrate, and preferably the laminated substrate has a rough surface layer with the above unevenness formed on it. The construction of the unevenness may be such that fine particles are dispersed and contained in a binder matrix. Alternatively, porous glass or porous ceramics may be used.
It is preferable that the above first member is provided with an uneven geometry at least on a part of its surface and that the above uneven geometry is formed in such a direction that the incident angle dependency of the above secondary electron emission coefficient is reduced for any of the orbits of the electron beam from the above electron source as well as of the electron beam reflected on the above target side.
It is preferable that the above first member is provided with an uneven,geometry at least on a part of its surface and that the above uneven geometry is formed in all directions parallel to the surface of the above first member.
When unevenness is formed in only one direction, for example, the effects of the unevenness is not expected in that direction; on the other hand, when the first member has a structure in which unevenness can be confirmed in any section cut in any direction, the effects of the unevenness occur for the incidence of the electrons with various incident angles. More concretely, effective is a structure having unevenness in such a manner that grooves and ribs are provided in two directions not parallel to each other or in such a manner that the axes of grooves and ribs are not provided in a fixed direction. A construction in which unevenness has a random distribution is also suitable.
In each of the above inventions, it is preferable that the above first member is provided with an uneven geometry at least on a part of its surface and the uneven geometry has the average cycle of 100 xcexcm or shorter, more preferably 10 xcexcm or shorter.
In each of the above inventions, it is preferable that the above first member is provided with an uneven geometry at least on a part of its surface and the uneven geometry has the average roughness ranging from 0.1 xcexcm to 100 xcexcm. It is more preferable that the uneven geometry has the average roughness ranging from 1 xcexcm to 10 xcexcm.
In each of the above inventions, it is suitable that the above first member is provided with an uneven geometry at least on a part of its surface and the uneven geometry consists of the cycles of at least two kinds of unevenness.
In each of the above inventions, it is suitable that the above first member is provided with an uneven geometry at least on a part of its surface and the uneven geometry is obtained by removing the material surface of the above first member nonuniformly.
Here, as a material subjected to the above nonuniform removal of the surface, the substrate underlying the film constituting the surface can be adopted, as shown in the paragraphs of the embodiment of the present application. In the embodiment of the present application, the substrate is provided with a film on its surface. As a method of the above nonuniform removal, the method of corroding the surface, more concretely, the method of forming grooves and holes on the surface chemically or electrochemically can be adopted. In addition, the nonuniform removal using a solid, for example, treatment with an sandpaper and treatment by spraying a group of particles, and the nonuniform removal using a liquid can be adopted. Alternatively, the unevenness may be obtained by subjecting the material to a pressure (nonuniform pressure) using the method of injection molding, rolling or roll stamping.
In each of the above inventions, it is preferable that the above first member is provided with a film at, least on a part of its surface and the above film has a sheet resistivity of 107 [xcexa9/xe2x96xa1] to 1014 [xcexa9/xe2x96xa1].
In each of the above inventions, it is preferable that the above first member is provided with a film at least on a part of its surface. And the film is suitably adopted which includes at least one kind of metal, carbon, silicon, or germanium and consists of nitride, oxide or carbide.
In each of the above inventions, it is preferable that the above first member is provided with a film at least on a part of its surface. And preferably the above film, when having been formed on a smooth substrate so as to have a smooth surface, has a composition which makes possible the secondary electron emission coefficient of 3.5 or less under vertical incident conditions.
In each of the above inventions, it is preferable that the above first member is provided with a film at least on a part of its surface and the surface of the above film has a high oxygen concentration as compared with the inside thereof.
The above first member is provided with a film at least on a part of its surface and the above film can be formed by any one of the following methods:
sputtering, vacuum deposition, wet printing, spraying, or dipping.
In each of the above inventions, preferably the above first member abuts the above electron source, preferably the above first member has a first film provided at least on a part of its surface and a conductive film provided on the portion where the above first film and the above electron source abut with each other, preferably the above first film and the above conductive film are in contact with each other, preferably the above first member abuts the electrode provided within the above hermetic container to control the electrons emitted from the above electron source, preferably the above first member has a first film provided at least on a part of its surface, and a low resistive film provided on the portion where the above first film and the above electrode abut with each other, and preferably the above first film and the above low resistive film are in contact with each other.
Preferably the above low resistive film has a low sheet resistivity as compared with the above first film. In particular, the above low resistive film has a sheet, resistivity lower than the above first film by an order of magnitude. In cases where the lowresistive film and the first film are in contact with each other, even if nonuniform charges exist in the first film, the low resistive film makes it possible to relax the nonuniformity of the charges. In the construction in which the first member and the electron source or the electrode abut with each other, when the construction contains a low resistive film at the portion where the above two abut with each other, a first configuration may be adopted where the substrate 1, the first film 2 and the low resistive film 3 are arranged in this order so that the low resistive film can directly abut the electron source or the electrode, as shown in FIG. 1. Or a second configuration may be adopted where the substrate 1, the low resistive film 3 and the first film 2 are arranged in this order so that the first film can directly abut the electron source or the electrode. In the first configuration, of course, the first film is electrically connected to the electron source or the electrode via the low resistive film. And in the second configuration, since the first film has a lower resistance in the direction of the film thickness at the portion where the first film and the electron source or the electrode abut with each other, the charges generated at some portion of the first film can move to the electron source or the electrode via the low resistive film and the touch portion of the first film. In other words, the first film is electrically connected to the electron source or the electrode via the low resistive film.
Each of the above inventions is effective in its application to the first member wanting to relax the effects of static electricity, and it is especially effective when the first member is a spacer for maintaining the space between the multiple members.
Each of the above inventions can be constructed in such a manner that it further comprises an electrode for controlling the electrons emitted from the above electron source within the above hermetic container. In particular, the above electrode, for example, may be an accelerating electrode which provides voltage to accelerate the electrons emitted from the electron source toward a target. Each of the above inventions is particularly effective in a construction where the voltage applied between the electron emission device contained in the above electron source and the above electrode is 3 kV or higher.
In the above construction comprising such an electrode, it is suitable that the above first member is provided with a film at least on a part of its surface and the above film is electrically connected to both of the above electron source and the above electrode. The electrical connection between the film and the electron source is implemented by allowing the film to electrically connect to the electrode, such as wiring, contained in the electron source.
In each of the above inventions, it is suitable that the above electron source has cold cathode devices as an electron emission device. As a cold cathode device, suitably used is surface conduction electron emission device. In each of the above inventions, particularly effective is the use of the electron emission device contained in the electron source which generates an electric field having a field device in the direction parallel to the main surface of the electron source when emitting electrons.
In each of the above inventions, preferably the above target is such one as produces images when being exposed to electrons. The one provided with fluorescent substances is suitably employed for the above target.
The invention of the electron beam apparatus according to the present application also includes the construction described below.
An electron beam apparatus comprising a hermetic container which includes an electron source having electron emission devices and targets exposed to the electrons emitted from the above electron source and further comprising a first member within the above hermetic container, characterized in that the above first member has a film on its surface, the foundation of the above film having an uneven geometry, the thickness of the above film being smaller than the height difference between the top and lowest portions of the unevenness of the above foundation.
In each of the above inventions, an electron source in which multiple rows of emission devices and multiple columns of electron emission devices are wired in a matrix can be suitably adopted. The electron source can be constructed in a simple matrix.
Alternatively, a construction can be also adopted in which a control electrode for modulation is provided besides the electron emission mechanism.
For example, an electron source having an ladder-shaped arrangement may be used in which multiple rows of wiring formed by connecting multiple electron emission devices (suitably cold cathode devices) in a row to each other at each of their ends are arranged, the electrons emitted from the above electron emission devices are controlled by a control electrode (also called grid) arranged over the above electron emission devices along the direction intersecting the above multiple rows of wiring.
According to the concept of the present invention, the present invention is applicable not only to an image producer suitable for displaying, but to a light emission source for the alternative to the light emitting diode etc. of all optical printer consisting of a photosensitive drum, light emitting diodes, etc. And the above image producer is applicable not only to a linear light emission source, but to a two-dimensional light emission source if the above m rows of wiring and n columns of wiring are properly selected. In this case, the image producing member is not limited to the substances directly emitting light, such as fluorescent substances used in the embodiments described below, but the member is also applicable on which a latent image is formed due to the charge by electrons. Further, according to the concept of the present invention, the present invention is applicable to the cases where the member exposed to the electrons from the electron source is other than image producing member such as fluorescent substances, for example, as is the case of electron microscopes. The present invention may be constituted of a general electron beam apparatus which does not specify a member exposed to the electrons.